Earticle

Purpose: This study aimed to provide basic data to identify the current status of use of maxillofacial prosthesis across the world and discuss its application and research directions in Korea. Methods: Existing literature (study period, 2010 to 2020) from international studies was collected from PsycINFO, CINAHL, and PubMed, whereas domestic studies were searched using KISS and RISS. Maxillofacial prosthesis was used as the search word. A total of three foreign and two domestic articles were searched, and as a result, a total of 12 documents were selected for analysis. Results: A total of 3,311 studies were searched in this study. Among them, 3,253 articles contained in duplicate inspection and exclusion criteria were removed, and 12 articles were selected by removing literature that did not meet the research criteria through title and green and text reviews. Finally, two researchers selected the final 12 articles through handwritten searches. Eleven of them were case studies, and the remaining one was a descriptive study. Conclusion: This study identified the current status of studies that implemented maxillofacial prosthesis, published from January 2010 to January 2020. Facial prosthetics improve the quality of life of patients by restoring defects that appear on different types of mouth and face and promote both function and aesthetics. Therefore, they can be used to treat various conditions and have a positive impact on the future.

Purpose: This study aimed to produce resin prosthetics using a dental barrel finishing machine. For dental resin grinding, the ingredients of the barrel finishing media were analyzed, and surface residues of the resin were observed. Methods: Two types of barrel finishing media for dental resin grinding were tested. Specimens were made from thermal polymerized, auto polymerized, and photopolymerized resins. Finishing media were analyzed through energy-dispersive X-ray spectroscopy (EDS) component analysis and inductively coupled plasma-optical emission spectrometry (ICPOES) component analysis. Then, the prepared specimen was barrel finished for 25 minutes using two types of barrel finishing media, and scanning electron microscope was photographed to observe the surface residues. Results: As a result of EDS component analysis, both types of finishing media were analyzed for the components of C, O, Zr and Al elements, and industry media (IM) was further analyzed for the components of Si and Mg elements. In the ICP-OES component analysis, Cd and As, which are harmful elements, were detected in IM, and no harmful elements were detected in manufacturing media (MM). Because of observation of surface residues, no residues were observed in the three types of resin specimens that were barrel finished with two types of finishing media. Conclusion: Surface residue wasn’t observed on the specimens polished using two types of finishing media. However, in IM, Cd and As, which are harmful elements, were detected, making it inappropriate for clinical use. In MM, harmful elements were not detected; therefore, clinical use will be possible.

Purpose: The purpose of this study was to assess the fitness of anterior and posterior interim crowns fabricated by three different additive manufacturing technologies. Methods: The working model was digitized, and single crowns (maxillary right central incisor and maxillary right first molar) were designed using computer-aided design software (DentalCad 2.2; exocad). On each abutment, interim crowns (n=60) were fabricated using three types of additive manufacturing technologies. Then, the abutment appearance and internal scan data of the interim crown was obtained using an intraoral scanner. The fitness of the interim crowns were evaluated by using the superimposition of the three-dimensional scan data (Geomagic Control X; 3D Systems). The one-way analysis of variance and Tukey posterior test were used to compare the results among groups (α=0.05). Results: A significant difference was found in the fitness of the interim crowns according to the type of additive manufacturing technology (p<0.05). The posterior interim crown showed smaller root mean square value than the anterior interim crown. Conclusion: Since the fitness of the posterior interim crown produced by three types of additive manufacturing technology were all within clinically acceptable range (<120 μm), it can be sufficiently used for the fabrication of interim crowns.

Purpose: In this study, when the etching treatment method, which is a chemical surface treatment method, is applied to colored zirconia, the shear bond strength between the veneering ceramic material and colored zirconia is compared with that without surface treatment, and the fracture type is observed to evaluate the etching treatment effect of colored zirconia. Methods: Experiments were conducted after dividing the study sample into two groups, which are the zirconia control group without surface treatment using colored zirconia blocks (without etching zirconia, NZC group) and the zirconia group treated with a commercially available etching solution (etching liquid zirconia, EZC group). Results: The mean shear bond strength of the NZC group was 20.31±2.32 Mpa, and that of the EZC group was 25.95±2.34 Mpa, and the difference between these two values was statistically significant (p<0.05). Further, the surface roughness Ra value was higher in the EZC group than in the NZC group. In the fracture pattern, cohesive fractures were dominant, and adhesive fractures and cohesive fractures were mixed. Conclusion: The bond strength was significantly higher in the group treated with colored zirconia. The fracture pattern was mostly cohesive failure in the group not treated with etching and changed to mixed failure as the etching treatment progressed.

Purpose: This study was conducted to investigate alloys spectrophotometrically including yttrium of nickel-chromium (Ni-Cr) alloys, which are used as substitutes for the regulation of beryllium and provide helpful improvements in Ni-Cr alloys. Methods: Four groups of specimens (ZN, ZY, SN and EM) were prepared for analysis. Color parameters were measured with a spectrophotometer, and color difference (ΔE*) was calculated. The t-test and one-way analysis of variance test were used to determine significant difference, and the Tukey test was used to identify where the differences were. To measure the spectroscopic reflectivity, the spectroscopic reflectance was measured and converted into CIE L*, a*, b* color system. Results: The ΔE* value of each metal ceramic group after opaque firing of Ni-Cr alloy with and without yttrium was <2, and the total group color difference (ΔE*) was below 1 in the dentin ceramic all experimental group. However, the a* and b* values of the metal ceramic groups were higher than that in the lithium disilicate all ceramic group, and the chroma was higher than the natural tooth. The brightness of all experimental groups was similar to that of the shade guide sample. Conclusion: Yttrium added to Ni-Cr alloys showed similar CIE L*, a*, b* values to Ni-Cr alloys that did not contain yttrium, indicating that yttrium had no effect on color in metallic ceramic systems.

Purpose: This study investigates the effect of repeated use of lithium disilicate glass-ceramics on color stability. Methods: In this study, 2 types of lithium disilicate glass-ceramics were used and they were divided into 4 groups after 1st, 2nd, 3rd, and 4th heat pressing. The L*, a*, and b* values of all specimens were measured using the VITA Easyshade Advance 4.0. These values was used to determine the ΔE value and transparency. IBM SPSS Statistics ver. 24.0, a statistical significance level of 0.05 and one-way ANOVA were used for all data. Results: In all groups, the L* and b* values were the lowest in the specimens subjected to the 4th heat pressing and the corresponding a* value was the highest. All specimens showed ΔE values of ≤3.3, indicating color changes that were not visible with the naked eye, and the color difference increased with the number of repeated heat pressing. The transparency of all specimens decreased as the number of repeated uses increased. Conclusion: According to the number of repeated heat pressing, the color difference of Rosetta SP (HASSBIO) was larger than that of IPS e.max Press (Ivoclar Vivadent), but it was clinically acceptable in all groups. Moreover, transparency decreased as the number of heat presses increased in all groups. According to the above findings, the lithium disilicate glass-ceramic has high color stability due to repeated heat pressing, implying that it can be used in clinical settings regularly.

Purpose: This study aims to make suggestions for the implementation of the job-based dental technician practical exam. Methods: The duties of dental technicians and the recent trends in the dental technician field were defined and identified, respectively, to achieve the purpose of the current study. The practical test system of domestic and foreign national tests was comparatively analyzed to seek improvements. Additionally, the direction of the practical test to be taken in the future was investigated through a public hearing of domestic experts. Results: As a result of this study, the job site of dental technicians was recently found to be undergoing many changes, and it can be observed that related laws and the work site have already changed. Comparison of overseas test systems showed that Korea was limited to a rather small evaluation range; in general, the scope of the evaluation of the practical tests in foreign countries was widely conducted. In the results of the public hearing, opinions exist that the evaluation range of the practical test was expanded and that new subjects were needed, but the opinion on the existence of practical difficulties was mainly mentioned. Conclusion: The evaluation range of the current practical examination subjects should be expanded and the evaluation of digital dental engineering subjects should be added to proceed with the job-based practical examination. However, it seems that efforts should be made gradually through various efforts in the future due to practical difficulties.

Purpose: The purpose of the study was to determine the general characteristics of students in dental technology departments; the correlations among their immersion in learning, class satisfaction, and academic achievement; factors influencing online learning experience; ways to improve students’ class satisfaction; and basic data for designing effective online courses. Methods: A total of 300 questionnaires were produced and distributed to dental technology students from September 29 through October 8, 2020. The outcome was analyzed using IBM SPSS Statistics ver. 25.0. A significance level of α=0.05 was used for reliable verification. Results: Immersion in learning, class satisfaction, and academic achievement were relatively high among students who studied on a regular basis, and class satisfaction and academic achievement were relatively high among students who studied with almost no interruption. Concerning the correlations between academic achievement, immersion in learning, and class satisfaction in online learning, the correlation between academic achievement and class satisfaction was the highest at r=0.862. Class satisfaction was the largest factor that influenced academic achievement, and the higher students’ immersion in learning and class satisfaction were, the higher their academic achievement was. Conclusion: The research is a case study that investigated the general characteristics of dental technology department students and the correlations among their immersion in learning, class satisfaction, and academic achievement. The study outcome could be used in determining factors that influence online learning and designing effective online courses that improve learner satisfaction.

Purpose: The purpose of this study is to investigate the relationship between clinical practice satisfaction, professional self-concept, and career identity among students of dental laboratory technology. Methods: From September 1 to September 15, 2021, data were collected through selfquestionnaires completed by 180 students with clinical practice experience. The collected data were analyzed using the IBM SPSS Statistics ver. 22.0 statistical program. Frequency and percentage, mean, standard deviation, t-test, ANOVA, correlation analysis, and linear regression analysis were performed to analyze the data. Results: The average scores for clinical practice satisfaction, professional self-concept, and career identity were 3.17, 3.03, and 2.46, respectively. There were significant correlations between students’ clinical practice satisfaction, professional self-concept, and career identity. There were positive correlations between clinical practice satisfaction and professional self-concept and between professional self-concept and career identity. Conclusion: Clinical practice satisfaction was found to play an important role in the formation of a positive professional self-concept as a dental technician. Therefore, a clinical practice program should be developed and implemented that can increase the satisfaction of clinical practice.

By classifying temporary denture production for surgical guides, digital guide-based surgery, and final prosthesis production, the problems of each process were assessed in advance and the factors that could be improved were confirmed in this study. The manufacturing process of fusion dental prosthesis uses virtual programs and computed tomography images to manufacture devices using the latest technologies of computer-aided design/computer- aided manufacturing and three-dimensional printing, which enables implants to be placed in the desired location in advance. Moreover, implant placement is not dependent on the skill and condition of the dentist, and because it uses a computer system, it can always be performed at a constant and optimal position. This can reduce the remanufacturing rate compared with the general method, shorten the treatment period, and eliminate patient discomfort. Unlike the traditional method of using impression materials and plaster models, digital fusion dental prostheses would be evaluated as a technology for producing prosthesis through professional design technology and communication.